Package com.google.ortools.constraintsolver

Class LocalSearchFilter

  • Direct Known Subclasses:
    IntVarLocalSearchFilter
    public class LocalSearchFilter
extends BaseObject
    Classes to which this template function can be applied to as of 04/2014.
    Usage: LocalSearchOperator* op = MakeLocalSearchOperator<Relocate>(...);
    class TwoOpt;
    class Relocate;
    class Exchange;
    class Cross;
    class MakeActiveOperator;
    class MakeInactiveOperator;
    class MakeChainInactiveOperator;
    class SwapActiveOperator;
    class ExtendedSwapActiveOperator;
    class MakeActiveAndRelocate;
    class RelocateAndMakeActiveOperator;
    class RelocateAndMakeInactiveOperator;
    Local Search Filters are used for fast neighbor pruning.
    Filtering a move is done in several phases:
    - in the Relax phase, filters determine which parts of their internals
    will be changed by the candidate, and modify intermediary State
    - in the Accept phase, filters check that the candidate is feasible,
    - if the Accept phase succeeds, the solver may decide to trigger a
    Synchronize phase that makes filters change their internal representation
    to the last candidate,
    - otherwise (Accept fails or the solver does not want to synchronize),
    a Revert phase makes filters erase any intermediary State generated by the
    Relax and Accept phases.
    A given filter has phases called with the following pattern:
    (Relax.Accept.Synchronize | Relax.Accept.Revert | Relax.Revert)*.
    Filters's Revert() is always called in the reverse order their Accept() was
    called, to allow late filters to use state done/undone by early filters'
    Accept()/Revert().

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean accept​(Assignment delta, Assignment deltadelta, long objective_min, long objective_max)
      Accepts a "delta" given the assignment with which the filter has been
      synchronized; the delta holds the variables which have been modified and
      their new value.
      If the filter represents a part of the global objective, its contribution
      must be between objective_min and objective_max.
      Sample: supposing one wants to maintain a[0,1] + b[0,1] <= 1,
      for the assignment (a,1), (b,0), the delta (b,1) will be rejected
      but the delta (a,0) will be accepted.
      TODO(user): Remove arguments when there are no more need for those.
      void Commit​(Assignment delta, Assignment deltadelta)
      Dual of Relax(), lets the filter know that the delta was accepted.
      void delete()  
      protected void finalize()  
      long getAcceptedObjectiveValue()
      Objective value from the last time Accept() was called and returned true.
      protected static long getCPtr​(LocalSearchFilter obj)  
      long getSynchronizedObjectiveValue()
      Objective value from last time Synchronize() was called.
      boolean isIncremental()  
      void Relax​(Assignment delta, Assignment deltadelta)
      Lets the filter know what delta and deltadelta will be passed in the next
      Accept().
      void Reset()
      Sets the filter to empty solution.
      void Revert()
      Cancels the changes made by the last Relax()/Accept() calls.
      protected void swigDirectorDisconnect()  
      protected static long swigRelease​(LocalSearchFilter obj)  
      void swigReleaseOwnership()  
      void swigTakeOwnership()  
      void synchronize​(Assignment assignment, Assignment delta)
      Synchronizes the filter with the current solution, delta being the
      difference with the solution passed to the previous call to Synchronize()
      or IncrementalSynchronize().

      • Methods inherited from class java.lang.Object

        clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Constructor Detail

      • LocalSearchFilter

        protected LocalSearchFilter​(long cPtr,
                            boolean cMemoryOwn)

      • LocalSearchFilter

        public LocalSearchFilter()

    • Method Detail

      • swigDirectorDisconnect

        protected void swigDirectorDisconnect()

      • swigReleaseOwnership

        public void swigReleaseOwnership()

      • swigTakeOwnership

        public void swigTakeOwnership()

      • Relax

        public void Relax​(Assignment delta,
                  Assignment deltadelta)
        Lets the filter know what delta and deltadelta will be passed in the next
        Accept().

      • Commit

        public void Commit​(Assignment delta,
                   Assignment deltadelta)
        Dual of Relax(), lets the filter know that the delta was accepted.

      • accept

        public boolean accept​(Assignment delta,
                      Assignment deltadelta,
                      long objective_min,
                      long objective_max)
        Accepts a "delta" given the assignment with which the filter has been
        synchronized; the delta holds the variables which have been modified and
        their new value.
        If the filter represents a part of the global objective, its contribution
        must be between objective_min and objective_max.
        Sample: supposing one wants to maintain a[0,1] + b[0,1] <= 1,
        for the assignment (a,1), (b,0), the delta (b,1) will be rejected
        but the delta (a,0) will be accepted.
        TODO(user): Remove arguments when there are no more need for those.

      • isIncremental

        public boolean isIncremental()

      • synchronize

        public void synchronize​(Assignment assignment,
                        Assignment delta)
        Synchronizes the filter with the current solution, delta being the
        difference with the solution passed to the previous call to Synchronize()
        or IncrementalSynchronize(). 'delta' can be used to incrementally
        synchronizing the filter with the new solution by only considering the
        changes in delta.

      • Revert

        public void Revert()
        Cancels the changes made by the last Relax()/Accept() calls.

      • Reset

        public void Reset()
        Sets the filter to empty solution.

      • getSynchronizedObjectiveValue

        public long getSynchronizedObjectiveValue()
        Objective value from last time Synchronize() was called.

      • getAcceptedObjectiveValue

        public long getAcceptedObjectiveValue()
        Objective value from the last time Accept() was called and returned true.